I don't recommend, they ban affiliates with services like yours. I have displayed their banner for some time on Daily Bitcoins, payment still missing...

And they won't tell you that you got banned until you ask them why they didn't pay you, and they don't refund the advertisers they just use the coins for whatever they want...

the only one i have used is feedzebirds.com so far, depends on what you are trying to advertise whether that will be good, and there are some huge accounts that suck up everything and, i would prefer lots of small accounts, with no way to control which users can retweet i'm finished there too for now, but as for past results, i have 13 referalls to an online game, 5 referals to vircurex that actually did a little trading, and a few hundred clicks to some other things, so its okay.